HTML
The markup that built the web.
Where it came from
HTML was proposed by Tim Berners-Lee in 1991 as the publishing language of the World Wide Web, derived from CERN's SGML. Version 2 (1995) and the browser wars of the late 90s shaped it; HTML5 (2014) made it a "living standard" that never freezes.
It is the only format every browser speaks — which is why almost everything else (email, ebooks, help files) is either HTML or a wrapper around it.
How it works
HTML is a tree of tags: 〈p〉paragraph〈/p〉, 〈a href〉link〈/a〉, 〈h1〉heading〈/h1〉. Browsers parse it into the DOM, a live object model, tolerating errors gracefully (a missing 〈/p〉 just closes itself).
Going HTML → Markdown is a lossy simplification: structure and links survive, but styling and scripts are dropped. UWC does the round-trip in your browser for clean, readable Markdown.
Convert HTML
Strip HTML down to Markdown for docs — or rebuild HTML — all client-side.